1. Field of the Invention
The present invention relates to the field of a server power supply, and more particularly to a compact server power supply having high power density.
2. Description of Related Art
With reference to FIG. 9A, a redundant power supply for a server has a primary side circuit 70, a transformer 701 and a secondary side circuit 71.
The primary side circuit 70 is electronically connected to an AC power source and decreases voltage of the AC power source.
The transformer 701 has a primary side and a secondary side. The primary side is electronically connected to the primary side circuit 70 and outputs an induced current to the secondary side.
The secondary side circuit 71 is electronically connected to the secondary side of the transformer 701 and converts the induced current to a DC power source. The secondary side circuit 71 has a current doubler and an Oring MOSFET. The current doubler is electronically connected to the secondary side of the transformer 701 and has two electronic switches 721, two inductors 722 and an output capacitor 723. The two electronic switches 721 are electronically connected to the secondary side of the transformer 701 in serial. A serial connecting node between the two electric switches 721 is ground of the DC power source. The two ends of the electronic switches 721 connected to the secondary side are respectively connected to ends of the inductors 722. The other ends of the inductors 722 are connected to a common node. The output capacitor 723 is electronically connected between the common end and the ground of the DC power source. The ORing MOSFET is electronically connected to the common node and a high voltage potential (+12V) of the DC power source.
With further reference to FIG. 9B, another redundant power supply for a server with lower power watt is similar to that of FIG. 9A, but uses another secondary side circuit 71a and a central-tapped transformer 701. The secondary side circuit 71a has a full wave rectifier 72a and an ORing MOSFET 73.
The full wave rectifier 72a has two electronic switches 721, an inductor 722 and an output capacitor 723. The electric switch 721 uses MOSFET having a source, drain and a gate. The sources of the two electric switches 721 are respectively connected to two ends of the secondary side. The two drains of the electric switches 721 are connected to a common node. One end of the inductor 722 is connected to the common. The output capacitor 723 is electronically connected to the other end of the inductor 722 and a central node of the secondary side. The central node of the secondary side of the transformer 701 is ground of the DC power source.
The ORing MOSFET 73 is electronically connected to the common node and a high voltage potential (+12V) of the DC power source.
To implement the detailed circuit of the redundant power supplies, a trace-layout for a printed circuit board has to be created and then electronic elements of the detailed circuit are soldered on the corresponding trace lines on the printed circuit board. With further reference to FIG. 10, a pattern of the trace-layout is shown. Since the redundant power supply has to supply DC power source with high power watt to the server, trace patterns of high voltage potential and ground 822, 823 for the DC power source require large sizes. The transformer 701, the electric switches 721, the inductors 722, the output capacitor 723 and the ORing MOSFET 73 are soldered on corresponding trace lines 821 on the printed circuit board 82.
With reference to FIGS. 11 and 12, a physical redundant power supply having multiple DC power outputs so that the circuit of the power supply has two primary side circuits, two transformers and two secondary side circuits. Therefore, the numbers of the electronic elements of the secondary side circuits are increased for the printed circuit board 82. The power supply has a casing 80, the printed circuit board 82, a fan 83 and a power output terminal set 84.
The casing 80 has a base 801 and a cover 802 mounted on the base 801.
The printed circuit board 82 is mounted in the casing 80, and has trace lines 821 on which the electronic elements soldered and trace patterns of the high voltage potential and ground 822, 823, as shown in FIG. 10.
The fan 83 is mounted next to one short side of the printed circuit board 82 in the casing 80.
The power output terminal set 84 having multiple DC power output terminals is mounted next to the other short side of the printed circuit board 82 in the casing 80 and soldered on the trace patterns of the high voltage potential and ground 822, 823, as shown in FIG. 10.
Since the server power supply requires multiple DC power outputs, the electronic elements of the secondary side circuits, the current doubler or full wave rectifier need more space of the printed circuit board. With reference to FIG. 12, a top plane view of the printed circuit board on which the electronic elements are soldered is shown. The electronic elements include the transistors 721, the inductors 722 and the output capacitors 723 between the transformer and the power output terminal set 84. The output capacitors 723 are lined up and next to one side of the power output terminal set. To reduce the length of the short side of the printed circuit board 82, the transistors 721 are parallel to the output capacitors 723 and vertically facing the power output terminal set 84. However, most server factories produce small servers, so the server power supply factories are required to manufacture compact server power supply. The arrangement of electronic elements on the printed circuit board is not an effective way to reduce the size of the printed circuit board. Therefore, higher power density of the power source is a goal pursued by power supply factory.
Further, different servers require the power supply with different power watts, so the printed circuit boards with different trace layouts are needed. That is, the power supply factories have to stock different printed circuit boards to manufacture different types of power supplies. However, the power supply factories need more storing space to stock the different printed circuit boards and to create different manufacturing processes. Therefore, the manufacturing processes are turning out to be more and more complex.
To overcome the shortcomings, the present invention provides a high power density compact power supply for a server to mitigate or obviate the aforementioned problems.